The present invention relates to a vehicle seat having a seat part and a backrest part swivellably arranged thereon as well as a backrest adjusting device for adjusting the inclination of the backrest part. The backrest adjusting device comprises at least one rod element which is arranged crosswise in the transition area between the backrest part and the seat part and is supported with its upper end on the backrest part and with its lower end on the seat part. The rod element is a control-arm-type lever whose upper end is coupled to the backrest part with respect to movements and whose lower end can be displaced for adjusting the inclination of the backrest part by means of a driving mechanism along a circular-arc-shaped path (KH) between end positions.
DE-OS 22 40 692 illustrates a vehicle seat having a seat part and a backrest part which is swivellably arranged thereon. A backrest adjusting device is provided which has at least one rod element in the form of a control-arm-type lever for adjusting the inclination of the backrest part. This control-arm-type lever is arranged crosswise in the transition area between the backrest part and the seat part. The upper end of the control-arm-type lever is supported on the backrest part and is coupled thereto with respect to movements. The lower end of the control-arm-type lever is supported by a driving mechanism on the seat part. For adjusting the inclination of the backrest part, the driving mechanism comprises a rocker which can be swivelled in the manner of a crank by a transmission, and to which the lower end of the control-arm-type lever is connected in an articulated manner and can be displaced along a circular arc between end positions. Together with the control-arm-type lever, the rocker forms a type of toggle lever drive.
It is a disadvantage of this known vehicle seat that the rocker, which can be swivelled by the transmission, must be arranged at a considerable distance in front of the backrest, so that the toggle lever drive has a lever effect which is suitable for adjusting the inclination of the backrest part. As a result, a relatively large amount of space is required on the vehicle seat. This requirement disadvantageously impairs the vehicle occupant's sitting comfort.
DE 17 55 333 C3 (corresponding to U.S. Pat. No. 3,583,762) shows a vehicle seat constructed as a bucket seat, and having a seat part and a backrest part which is swivellably arranged thereon. For adjusting the inclination of the backrest part, this vehicle seat comprises a backrest adjusting device with at least one rod element which is arranged crosswise in the transition area between the backrest part and the seat part. For this purpose, the rod element, which is constructed as a threaded spindle, engages by its upper and lower end respectively. The threaded nuts are arranged on the backrest part and the seat part of the vehicle seat and have threads in opposite directions. By rotating the threaded spindle by way of a hand wheel fastened thereto, the spacing of the threaded nuts arranged on the seat part and the backrest part can be changed and the inclination of the backrest part can thereby be adjusted with respect to the seat part.
In this known vehicle seat, the adjustment of the inclination of the seat part by rotating the threaded spindle is, however, not very comfortable. In addition, the threaded spindle requires a relatively large amount of space, in which case, laterally in the area between the seat part and the backrest part, the seat cheeks and backrest must be cut out to a relatively large extent in order to ensure a free accessibility to the hand wheel of the threaded spindle. In one embodiment in which threaded rods are provided on both sides of the vehicle seat, no protection device is provided with respect to a non-uniform rotation of both threaded rods so it is possible that the two rod elements may be deformed.